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Message-ID: <CAE4R7bByr2tMv56DHFyee0KRz0dGtoZgjcxfLtefh2rH_-H7bA@mail.gmail.com>
Date: Sat, 9 May 2015 23:14:00 -0700
From: Scott Feldman <sfeldma@...il.com>
To: Jiri Pirko <jiri@...nulli.us>
Cc: Netdev <netdev@...r.kernel.org>,
Roopa Prabhu <roopa@...ulusnetworks.com>,
Guenter Roeck <linux@...ck-us.net>,
Florian Fainelli <f.fainelli@...il.com>,
"andrew@...n.ch" <andrew@...n.ch>,
"simon.horman@...ronome.com" <simon.horman@...ronome.com>,
Joe Perches <joe@...ches.com>,
"Samudrala, Sridhar" <sridhar.samudrala@...el.com>,
"Arad, Ronen" <ronen.arad@...el.com>
Subject: Re: [PATCH net-next v6 05/23] rocker: support prepare-commit
transaction model
On Sat, May 9, 2015 at 11:18 AM, Jiri Pirko <jiri@...nulli.us> wrote:
> Sat, May 09, 2015 at 07:40:07PM CEST, sfeldma@...il.com wrote:
>>From: Scott Feldman <sfeldma@...il.com>
>>
>>For rocker, support prepare-commit transaction model for setting attributes
>>(and for adding objects). This requires rocker to preallocate memory
>>needed for the commit up front in the prepare phase. Since rtnl_lock is
>>held between prepare-commit, store the allocated memory on a queue hanging
>>off of the rocker_port. Also, in prepare phase, do everything right up to
>>calling into HW. The same code paths are tranversed in the driver for both
>>prepare and commit phases. In some cases, any state modified in the
>>prepare phase must be reverted before returning so the commit phase makes
>>the same decisions.
>>
>>As a consequence of holding rtnl_lock in process context for all attr sets
>>(and obj adds), all memory is GFP_KERNEL allocated and we don't need to
>>busy spin waiting for the device to complete the command. So the bulk of
>>this patch is simplifying the memory allocations to only use GFP_KERNEL and
>>to remove the nowait flag and busy spin loop.
>>
>>Signed-off-by: Scott Feldman <sfeldma@...il.com>
>>---
>> drivers/net/ethernet/rocker/rocker.c | 393 +++++++++++++++++++++++-----------
>> 1 file changed, 271 insertions(+), 122 deletions(-)
>>
>
> ...
>
>>+static void *__rocker_port_alloc(struct rocker_port *rocker_port,
>>+ size_t size, gfp_t flags,
>>+ void *(*alloc)(size_t size, gfp_t flags))
>>+{
>
> you can omit alloc param here, since __rocker_port_alloc is called
> always with kzalloc. Also, flags is always GFP_KERNEL, but I have no
> problem in having that.
fixed for v7
> also, __rocker_port_alloc sond to me like it allocates actual port.
> Maybe "__rocker_per_port_alloc" or something like that?
> (same goes to other functions of similar name)
It's now __rocker_port_mem_alloc.
>>+ struct list_head *elem = NULL;
>>+
>>+ /* If in transaction prepare phase, allocate the memory
>>+ * and enqueue it on a per-port list. If in transaction
>>+ * commit phase, dequeue the memory from the per-port list
>>+ * rather than re-allocating the memory. The idea is the
>>+ * driver code paths for prepare and commit are identical
>>+ * so the memory allocated in the prepare phase is the
>>+ * memory used in the commit phase.
>>+ */
>>+
>>+ switch (rocker_port->trans) {
>>+ case SWITCHDEV_TRANS_PREPARE:
>>+ elem = alloc(size + sizeof(*elem), flags);
>>+ if (!elem)
>>+ return NULL;
>>+ list_add_tail(elem, &rocker_port->trans_mem);
>>+ break;
>>+ case SWITCHDEV_TRANS_COMMIT:
>>+ BUG_ON(list_empty(&rocker_port->trans_mem));
>>+ elem = rocker_port->trans_mem.next;
>>+ list_del_init(elem);
>>+ break;
>>+ case SWITCHDEV_TRANS_NONE:
>>+ elem = alloc(size + sizeof(*elem), flags);
>>+ if (elem)
>>+ INIT_LIST_HEAD(elem);
>>+ break;
>
> I must say I don't like propagating SWITCHDEV_TRANS_* this deep into
> driver. Also I don't like storing it in rocker_port->trans. I believe
> that is should be seen only by rocker_port_attr_set. Then functions with
> proper params should be called inside driver.
Ok, switched to passing it as param for v7
>
>
> ...
>
>> static int rocker_cmd_exec(struct rocker *rocker,
>> struct rocker_port *rocker_port,
>> rocker_cmd_cb_t prepare, void *prepare_priv,
>>- rocker_cmd_cb_t process, void *process_priv,
>>- bool nowait)
>>+ rocker_cmd_cb_t process, void *process_priv)
>> {
>> struct rocker_desc_info *desc_info;
>> struct rocker_wait *wait;
>> unsigned long flags;
>> int err;
>>
>>- wait = rocker_wait_create(nowait ? GFP_ATOMIC : GFP_KERNEL);
>>+ wait = rocker_wait_create(rocker_port);
>> if (!wait)
>> return -ENOMEM;
>>- wait->nowait = nowait;
>>
>> spin_lock_irqsave(&rocker->cmd_ring_lock, flags);
>>+
> ^^^
>> desc_info = rocker_desc_head_get(&rocker->cmd_ring);
>> if (!desc_info) {
>> spin_unlock_irqrestore(&rocker->cmd_ring_lock, flags);
>> err = -EAGAIN;
>> goto out;
>> }
>>+
> ^^^
>
>> err = prepare(rocker, rocker_port, desc_info, prepare_priv);
>> if (err) {
>> spin_unlock_irqrestore(&rocker->cmd_ring_lock, flags);
>> goto out;
>> }
>>+
> ^^^ not sure why you adding these lines.
Readability: put some white space between logical chunks.
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